In wireless communications systems, a front-end module (FEM) provides an interface between an antenna and an RF transceiver. A FEM typically includes power amplifiers, switches, low-noise amplifiers, control circuitry, and passive elements. Radio frequency (RF) Silicon on Insulator (SOI) has rapidly evolved as a mainstream technology for switches used in wireless applications. A high power transmit-receive switch with a traditional configuration generally utilizes a large number of large sized stacked devices. Because of the large number and size of the stacked devices, traditional high power switches use a large die area. The large number and size of the stacked devices also has negative effects through substrate loss and parasitic substrate capacitance. Due to large gate capacitance, fast switching time (e.g., <0.5 microsecond) is hard to implement with traditional switches without degradation of insertion loss. Applications with traditional high power switches involve a trade-off between insertion loss and fast switching time through gate resistance. Obtaining a low return loss is also difficult due to large parasitic substrate capacitance.
It would be desirable to implement a high power SOI switch that avoids the negative effects described above.